Identify the topic sentence from the following paragraph. There are many things that ESL students can do to improve their English more quickly. They can join an after-school club which will give them the chance to practise spoken English while doing an activity that they enjoy. They can also watch films, particularly DVDs with the English subtitles turned on. Best of all, however, is to do plenty of reading for pleasure. Non-fiction in particular is an excellent way of acquiring a strong academic vocabulary.